The invention relates to an arrangement for automatically denesting containers in lying position and nested in each other, the containers being deposited on a support, e.g. a conveyor, with the container opening facing upward, the arrangement comprising gripping means for gripping and moving out a respective first container of a lying container stack, the gripping means being arranged on holding elements movable in the direction of the stack, and further comprising clamping means for holding back the lying container stack, with the foremost container being left free.
Containers which as a rule have frusto-conical shapes, i.e. have oblique walls, are stored in stacks in warehouse stocks or in commissioning systems, e.g., and they must be denested again before use and supplied individually for filling. Denesting should occur rapidly and gently and, in particular, it should be automated since the individual containers are supplied to conveying means in intermittent manner, and manual denesting would be very laborious.
In DE 3 042 903 A, automatic denesting has been described. Here, a lifting mechanism is provided which engages the respective uppermost container of a vertical container stack advanced on a conveyor belt, which lifts this uppermost container and which deposits it on a conveyor belt. What is of disadvantage is that the lifting mechanism is relatively complex in construction, primarily since it must engage containers at ever changing levels; moreover, the vertical container stacks pose problems if they have to be advanced over larger distances since, in case of major stack heights, they have little stability and topple easily if their movement is started or stopped with jerks.
According to U.S. Pat. No. 4,915,578 A, a vertical container stack is top-delivered to a holding device, the lowermost container being left free so that it drops onto a conveyor belt provided therebelow and is moved off by aid of the same. In detail, two oppositely arranged flange rims of the containers lie on projecting tooth ledges of a chain, which tooth ledges guide the containers downwardly in still stacked manner. By means of projections engaging the two oppositely arranged rims of the lowermost container from above, a second chain moving faster and in counter-direction pushes this lowermost container from the stack downwards to below so that it drops to the conveyor belt at last and is transported away. Here, too, it is a disadvantage that the stack is provided vertically, with the risk of tilting, as already described before, primarily in case of major stack heights. Moreover, the devices used must be built high, increasing construction costs. The container stack must not exceed a certain height also because otherwise it would become too heavy and the stack could no longer be carried by the device.
In U.S. Pat. No. 4,983,098 A, an arrangement of the present type is described, for providing cup-shaped conical containers individually before they are filled and closed, the containers being delivered in vertical stacks which are turned over. From the lying container stack, the foremost container is gripped by vertically movable lug members which then are moved horizontally together with the foremost container so as to pull it away from the remaining stack. At the same time, the second container is held back by like, vertically movable lug members. To be put into an upright position, the foremost container moves against a pivotable hook member which grips the upper container rim at its inner side so that the container is decelerated at its upper rim while it is transported on on the conveyor; this results in upright tilting of the container. A disadvantage is that the lug members which engage behind the container rims with one of their legs must be precisely adapted to the containers and that their vertical movement requires a relatively complex driving means which in parts must be mounted laterally of the conveyor.
In U.S. Pat. No. 4,054,212 A, finally, an arrangement for downwardly tilting cup-shaped containers, bottoms first, is described, wherein this denesting should be effected in an automatic drink dispenser. The cups are pushed forwards by pivotable ram arms via arcuate rails until they fall into a holding means on a conveyor. At the same time, the second cup of the stack is kept back by gripping fingers. This construction is provided for denesting cups, and it is hardly suitable for containers of substantially larger mass.
It is an object of the invention to provide an arrangement for denesting, as initially indicated, with which it is possible to denest nested containers in a rapid and reliable manner, by using simple construction measures, as well as with a high flexibility as regards container dimensions.
The arrangement according to the invention of the initially defined kind is characterized in that the gripping means is provided with lateral pressure-medium cylinders which have horizontal axes on the same level and which are connected with the holding elements extending thereabove. Because of the lying posture of the container stack, the structural height of the arrangement can be a low one, and also the containers need not be lifted or need be lifted only slightly. Thus, the xe2x80x9coverheadxe2x80x9d-arrangement of the holding elements does not pose any problems. The use of pressure medium cylinders for the gripping means allows for a simple mode of construction, while nevertheless an easy, reliable and rapid gripping of the foremost container is possible. Since the pressure medium cylinders have horizontal axes on the same level, the foremost container is tightly held between the pressure medium cylinders, with the containers neither tilting nor sliding off-center.
The entire lying or horizontal container stack can be lifted from its support by a lifting mechanism before the foremost container is moved on, the lifting mechanism being capable of reaching between rollers of a roller conveyor provided as support, e.g.; the lifting mechanism may, however, also be built with rails or lifting ledges engaging laterally on the lower side of the container stack, in which case the stack support may also be formed by a conveying belt. Lifting of the container stack reliably prevents frictional sliding of the first container along the support while it is being pulled away from the container stack. Apart from the fact that the containers and the conveyor are carefully treated thereby, in this manner the amount of energy employed is minimized.
The pressure medium cylinders provided according to the invention may engage the respective container frictionally or positively, and suitably they are simply released from the container after the respective container has been moved away from the remaining stack and after it has been pivoted, and thus this container is simply dropped onto its support; the dropping height may be low so that a gentle xe2x80x9cdepositingxe2x80x9d of the containers nevertheless is ensured. The pressure medium cylinders are to be designed such that they are capable of transmitting the respective transverse forces; optionally, also a lever mechanism can be provided. For pivoting of the containers while providing them individually, it is particularly advantageous if the pressure medium cylinders are rotatably arranged on the holding elements.
It is particularly advantageous if the holding elements are mounted to be linearly displaceable in parallel to the container stack. In this manner, the foremost container is linearly moved away from the remaining container stack. The foremost container suitably is gripped at its opening rim or collar facing rearwards, and is pushed from the container stack with its bottom facing forwards, the container bottom of the foremost container at least in the starting phase of pushing from the stack being located at a distance above the support so that the container does not chafe on the support.
The pressure medium cylinders, or their piston rods, respectively, may be oriented coaxially, and may be provided with a rubber head or the like with which they can be pressed softly against the container and safely against slipping aside therefrom. In the case of rotatable pressure medium cylinders, simple pivoting of the foremost container about the horizontal axis of the pressure medium cylinder into a substantially horizontal position is enabled, i.e. with the opening facing upwards, wherein only the pressure medium cylinders carry out a rotational movement and other parts of the gripping means would not have to be rotated.
Moreover, it is advantageous if the holding element, e.g. the legs of a frame, are mounted on a linear guide. In this case, a pressure medium cylinder may press the frame in the direction away from the container stack, and by the frame it is ensured that both sides of the container will be gripped and moved simultaneously, whereby the container will remain exactly straightly aligned and not get stuck by jamming, e.g. because of a slight turning out of this longitudinal alignment on the container stack.
For a simple depositing of the containers, it is particularly advantageous if the support receiving the denested containers is preceded by an edge provided at a higher level relative thereto, for tilting of the individual containers. After the foremost container has been moved out of the container stack as described above, it is moved in lying posture, with the container bottom facing forwards, to the edge, and there it is released for turning by tilting about this edge and for deposit on the support following the edge, e.g. a conveyor. In this case, the container must be pulled away from the next container merely by a short distance, and it can be guided to the edge by means of a conveyor, e.g. a conveyor belt or a roller conveyor. As soon as a sufficiently large part of the container projects beyond this edge, it will tilt, as a consequence of gravity, with the container bottom downwards to the support located at a somewhat lower level, and there it comes to stand upright. From there it will be led away immediately to make room for the next container. The edge will be provided as close to the denesting arrangement proper as possible, so that the individual lying container need not be transported far before it tilts onto the support. In terms of construction it is also possible to make the height difference of these two supports adjustable, e.g. in that the consecutive support is shiftable in terms of height, or in that it is mounted to be pivotable about an axis, wherein, optionally, an ascent or a descent is brought about. In this manner, differently sized containers can be provided individually. To avoid rubbing of the containers along the support, the pressure medium cylinders here preferably are not rotatable, but fixedly mounted on the holding elements, and thus they carry the entire mass of the container.
A further preferred arrangement is characterized by a cam control for the holding elements so as to move the foremost container according to a predetermined, in particular arcuate, movement out of the container stack and deposit it on the support, e.g. the conveyor, by pivoting it into a position with the container opening facing upwards. The amount by which the container is lifted will depend on the depth of the container. In any event, by the pivoting movement, slipping of the container on the support and thus an increased frictional resistance can largely be avoided. The container openings of the containers in the lying container stack may face forwards, whereby pulling out and turning of the respective foremost containers can be realized particularly simply in one single, continuous movement. Yet the containers may also be provided with the container bottom facing forward, in which case pivoting of the container will be caused only after the foremost container has been pulled away from the stack.
As has already been suggested, in the last-mentioned embodiment, it is advantageous for minimizing movement during denesting if the foremost container is moved away from the lying container stack with its opening facing forward. While the foremost container is moved out and upwards, it will tilt automatically into a position with the container opening facing upwards, most simply by the container""s center of gravity being arranged behind or below the point of engagement of the gripping means on the container, whereby the container seeks to assume the lowermost position.
To controlledly pull the foremost container out of the container stack it is also advantageous if the holding elements, e.g. the legs of a frame, are pivotably mounted. In this manner, the various individual movements of the foremost container will be combined and coordinated with each other in a very simple manner: At the same time as the first container is pulled out of the container stack, the axis of the pressure medium cylinders and thus also of the containers is arcuately moved forward and upwards by the pivotal movement of the holding elements, which movement is assisted by the oblique container walls, since in this manner, frictional slipping of the container on the support is prevented; when pivoted further, the container finally assumes its position with the opening facing upwards.
The holding elements may also have an associated connecting-link guide or a four-bar linkage for control of their movement. The movement of the holding elements and, thus, of the containers may be optimized so that merely minimal lifting of each foremost container is effected while it is being pulled away from the stack, without lifting the container for an unnecessary large distance to then lower it immediately thereafter and to put it onto the support.
To efficiently effect the translation or pivotal movement of the holding elements, preferably pressure medium cylinders are provided as drive for the holding elements.
To grip the foremost container particularly tightly, it is advantageous if the gripping means comprises gripping jaws to be pressed against the container, which are attached on pivoting levers engaged by the pressure medium cylinders. The pivoting levers in this case are pivotably mounted, e.g. on brackets fixedly attached on the holding elements. By actuating the pressure medium cylinders, the pivoting levers are pivoted about their pivot axis, and thus the gripping jaws are pressed against the foremost container. Should the foremost container be jammed in the next container, the gripping jaws are further pivoted by the forward movement of the holding elements and pressed more tightly against the foremost container. This increases the pressing effect, and the foremost container will reliably be moved out of the container stack.
To pull the first container out of the container stack, a particularly simple construction becomes possible if the clamping means contains a pressure medium cylinder which presses at least the second container in the stack downwards, preferably in combination with a lifting mechanism which lifts the entire lying container stack.
To ensure a safe positioning and holding back of the container stack, the clamping means may also have an associated stop for the container stack, which stop can be moved out of the way of the containers, e.g. by pivoting. The arriving container stack is stopped by the stop at precisely the correct position for clamping retention. While subsequently the gripping means grips the foremost container, the stop can, quickly be moved out of the way, e.g. by pivoting, so that removal of the foremost container from the container stack will not be impeded thereby. After this container has been removed, the stop can be activated again so as to stop the remaining container stack, which has been moved forward in the correct position regarding the clamping means. It is also possible that one stop is provided on each lontigudinal side of the container stack on the support, e.g. on the conveyor.
Moreover, it is also advantageous if a trigger photoelectric barrier is provided for actuating the pressure medium cylinder and/or the stop. In that case, the trigger photoelectric barrier exactly controls the temporally correct actuation of the pressure medium cylinder and or the stop, respectively, if the container stack is moved forwards in each instance. The trigger photoelectric barrier may, e.g., be provided on the support in the region of the lifting means or laterally on the stand.
It is also advantageous if a monitoring photoelectric barrier is provided for sensing the remaining containers of the stack. With this, the clamping means can be switched off if all the containers of a stack have been provided individually, and/or a further container stack can be requested in time.
Optionally, a vertical container stack may be turned over to the horizontal on a conveyor prior to denesting, so as to provide the container stack in lying posture. In this manner, the containers may previously be stacked to a vertical container stack which, as a rule, is easier than stacking in lying posture. For denesting, suitably already turned, lying container stacks are supplied so that their advancing can be effected without any problems, wherein also several turned container stacks may be slid into one another prior to denesting.
Accordingly, it is suitable if the gripping means is preceded by a pneumatically actuated stack turning device. Thus, stacking of the containers may be effected in vertical state and denesting them in lying state. By the pneumatic actuation, simple control and reliable functioning of the stack turning device is achieved.
A stack turning device of advantageous function is obtained if it comprises a stack sliding support which is vertical in the resting position and is pivotable about a horizontal axle. The vertically upright container stack leans against this sliding support. The sliding support is at least as long as the container stack is high so as to support the latter during the turning movement. The sliding support pivots, e.g. by aid of a pressure medium cylinder, about an upper horizontal axis, the lower end moving the lowermost containers of the container stack out of the upright position so that the stack begins to tilt. For a minimum force to be applied, the axle about which the sliding support tilts is provided in the upper region of the sliding support, whereas the pressure medium cylinder driving it engages as low on the sliding support as possible, whereby the lever action is best utilized. The container stack is supported by the sliding support while being turned to a lying posture, the pivot movement of the sliding support being continued such that both the sliding support and the container stack assume an ever more slanted position, yet with the lowermost container always remaining in xe2x80x9cbottomxe2x80x9d contact (with the conveyor). As soon as a certain minimum inclination has been attained, the container stack will slide down along the sliding support and thus will come to lie. Such sliding is assisted by a guided movement of the lowermost or foremost container, respectively, on the support, e.g. by the support being a driven conveyor, e.g. a conveyor belt. The latter may immediately transport away the lying container stack so as to make room for the next container stack. The next upright container stack is brought to the turning device by a conveyor so that the stack again abuts on the sliding support which meanwhile has been pivoted back into its starting position.
A particularly advantageous construction provides that a roller is provided opposite the sliding support on a stand, which roller forms a stack stop when turning the stack into the horizontal position. This roller may be mounted on a transverse beam of the stand so that the upper stack region abuts on the roller and is held back by the latter while the sliding support carries out its pivotal movement. Also several rollers mounted on the stand in spaced-apart relationship would be conceivable.
A simple, efficient construction is also obtained if the stack turning device comprises angled forked arms mounted so as to be pivotable about their horizontal angle axis. In that instance thexe2x80x94verticalxe2x80x94container stack is pushed onto the one fork arms until it comes to abut on the upright second fork arms provided approximately at right angles to the former. The upright fork arms subsequently are pivoted into the horizontal, thereby acting as support for the stack which simultaneously is held by the other, originally horizontal fork arms, which are tilted up into a vertical position, so that in doing so, the stack is always kept and manipulated under control.
A particularly preferred construction is characterized in that the stack turning device comprises supporting devices for the container stack, which are movable relative to each other and which have associated separate pressure medium cylinders for their independent pivotal movement. These supporting devices may, e.g., be two pairs of fork arms which are pivotable upwards and downwards independently of each other about a mutual horizontal axis or about separate horizontal axes of their own, in the region of the support, i.e. the conveyor.
For a continuous operation of the automatic denesting, a container rotating device for rotating the denested box-type containers from their transverse orientation into a longitudinal orientation is advantageous. In this manner, the containers are automatically moved on in the longitudinal orientation usually desired in commissioning systems, e.g., and this even if the containers are obtained in transverse orientation after denesting, which frequently will be the case since with lying stacks, for reasons of stability the containers will arrive with their larger side face lying on the conveyor.
For use in commissioning systems, it is also advantageous if the container rotating device has an associated control unit for rotating each container with a pre-determined side facing forward. In commissioning systems, in most instances the front walls of the containers carry documents, codes etc. which are important for the controlled movement of the container through the commissioning system and for its filling. In that instance, reading units are provided in the commissioning system for the proper function of which the correct orientation of the containers is important.
A particularly simple construction of the rotating device consists in that it comprises two stops, e.g. cylinders, adjacently arranged on the conveyor provided as the support and selectively projectable across the conveying plane, after which the conveyor preferably narrows. Depending on the direction in which the container is to be rotated, one or the other cylinder lowers so that it no longer projects from the conveying plane. The container which has been advanced is stopped on one of its sides by the one projecting cylinder, while the other side of the container is moved on by the conveyor. This results in a rotation of the container about the protruding cylinder, past which it is guided. The guides on both sides of the conveyor narrow in transporting direction until the distance between them allows only the passage of a longitudinally oriented container. In this narrowed portion, the container which has already been rotated to some extent is forced to a complete longitudinal orientation.
As has already been mentioned, according to the present invention stacks of differently high containers can be denested without any problems. For the differently high containers subsequently being specifically usable for their respective tasks, they have to be distributed according to their heights. Accordingly, preferably a shunting means is provided for distributing the individually provided box-type containers to various conveying paths, e.g. in accordance with their container height. In most instances, two consecutive conveyors will be present, at least one pivotable lever or pivot arm in each case merely leaving the desired consecutive conveyor accessible by which the container is to be conveyed, and blocking access to the other consecutive conveyor.
For a simple recognition of the container height of the container which has just arrived, it is advantageous if the shunting means has a preceding container height sensor, e.g. with photoelectric barriers at different levels. If a container of a certain height is moved past the sensor, the latter senses this and transmits a signal corresponding to the sensed container height, for pivoting the lever or pivot arm into a certain position.